The way to tell that is to measure the neck straightness. If it's too bent, you need more truss (righty tighty). If it's too straight, you need less (lefty loosey). How do you measure it? I use a capo on the first fret, hold down the fret where the neck joins the body with my right hand, and slide a feeler gauge under the B string. Slide it between the string and the fret around 7, 8, 9. If you can slip it in without raising the string you have at least that much neck relief (or more). I see folks online recommending 12 or 14 for a B string. I have run mine as low as 10 if I can get away with it without buzz. Remember: this is a measure of neck straightness, not string height, which is a separate thing. (A set of feeler gauges can be bought at any hardware store for less than $10. If you want to know more, PM me. Or just peruse the "repair and setup" forums.)